Use of dual-phase helical CT improves prediction of resectability in patients with pancreatic cancer. CT angiography cannot show all of the findings seen on helical scans.

ObjectiveThis prospective study was undertaken to evaluate the accuracy of a noninvasive "all-inone" staging method in predicting surgical resectability in patients with pancreatic or periampullary tumors. Summary Background DataDespite progress in imaging techniques, accurate staging and correct prediction of resectability remains one of the chief problems in the management of pancreatic tumors. Staging algorithms designed to separate operable from inoperable patients to save the latter an unnecessary laparotomy are becoming increasingly complex, expensive, timeconsuming, invasive, and not without risks for the patient. MethodsBetween August 1996 and February 1997, 58 consecutive patients referred for operation of a pancreatic or periampullary tumor were examined clinically and by 5 staging methods: 1) percutaneous ultrasonography (US); 2) ultrafast magnetic resonance imaging (UMRI); 3) dual-phase helical computed tomography (CT); 4) selective visceral angiography; and 5) endoscopic cholangiopancreatography (ERCP). The assessment of resectability by each procedure was verified by surgical exploration and histologic examination. ResultsThe study comprised 40 male and 18 female patients with a median age of 63 years. Thirty-five lesions were located in the pancreatic head (60%), 11 in the body (19%), and 1 in the tail of the gland (2%); there were 9 tumors of the ampulla (16%) and 2 of the distal common duct (3%). All five staging methods were completed in 36 patients. For reasons ranging from metallic implants to contrast medium allergy or because investigations already had been performed elsewhere, US was completed in 57 (98%), UMRI in 54 (93%), CT in 49 (84%), angiography in 48 (83%), and ERCP in 49 (84%) of these 58 patients. Signs of unresectability found were vascular involvement in 22 (38%), extrapancreatic tumor spread in 16 (26%), liver metastases in 10 (17%), lymph node involvement in 6 (10%), and peritoneal nodules in only 2 patients (3%). These findings were collated with those of surgical exploration in 47 patients (81 %) and percutaneous biopsy in 5 (9%); such invasive 393

The purpose of this study was to evaluate the correlation of radiation dose with image quality in spiral CT. Seven clinical protocols were measured in six different radiological departments provided with four different types of high specification spiral CT scanners. Central and surface absorbed doses were measured in acrylic. The practical CT dose index (PCTDI) was calculated for seven clinical examination protocols and one standardized protocol using identical parameters on four different spiral CT scanners with a dedicated ionization chamber inserted into PMMA phantoms. For low contrast measurements, a cylindrical three-dimensional (3D) phantom (different sized spheres of defined contrast) was used. Image noise was measured with a cylindrical water phantom and high contrast resolution with a Perspex hole phantom. Image quality phantoms were scanned using the parameters of the clinical protocols. Images were randomized, blinded and read by six radiologists (one from each institution). PCTDI values for four different scanners varied up to a factor between 1.5 (centre) and 2.2 (surface) for the standardized protocol. A greater degree of variation was observed for seven clinical examination protocols of the six radiological departments. For example, PCTDI varied up to a factor between 1.7 (cerebrum protocol) and 8.3 (abdomen paediatric protocol). Low contrast resolution correlates closely with dose. An improvement in detection from 8 mm to 4 mm sized spheres needs approximately a ten-fold increase in dose. Noise shows a moderate correlation with PCTDI. High contrast resolution of clinical protocols is independent of PCTDI within a certain range. Differences in modern CT scanner technology seem to be of less importance for radiation exposure than selection of protocol parameters in different radiological institutes. Future discussion on guidelines regarding optimal (patient adapted) tube current for clinical protocols is desirable.

Hyperlipasemia is a common finding in critically ill patients without prior pancreatic disorder. While elevated serum PAP levels indicate pancreatic cellular stress morphological alterations of the pancreas are rare and of little clinical importance.

Contrast-detail measurements were performed on a computed radiography imaging system as a function of detector entrance air kerma over the dose range from 0.743 microGy (0.085 mR) to 277 microGy (31.8 mR). A theoretical model of contrast-detail behaviour for a photostimulable phosphor computed radiography system has been derived, which is based on a modified version of the Rose theory of threshold detection. Included in the model are both system and x-ray quantum noise terms, as well as the response of the eye. The zero-frequency noise power of the computed film images was measured with a double-beam scanning microdensitometer. For a given detector dose, good agreement was found between the predicted and measured data when this measurement of system noise was included in the model. The contrast-detail results obtained for the computed radiography system were also compared with contrast-detail results for an image intensifier-TV based digital imaging system and a conventional film-screen system.